The present invention relates generally to drainage systems and, more particularly, to a drainage channel or trench having a removable pin securing a grate spanning the trench.
Drainage and other trenches of various sizes and shapes are desirable for a number of applications. For example, manufacturing facilities typically require drainage systems that include trenches formed in the building floors to collect, remove, and/or recycle excess water or other liquids. In addition, numerous outdoor industrial and commercial sites, such as parking lots, require drainage systems, including trenches, to collect and direct rainwater and other liquids to underground storm sewers to prevent flooding and to decrease run-off. Similarly, roadways and the like may also require drainage systems, including trenches.
In the past, these trenches have generally been formed by first placing and securing a form of predetermined shape in a ditch that has previously been formed in the ground. A moldable trench forming composition, such as cementitious material, is then poured around the form and is allowed to set. Once the cementitious material has set, the form is removed from the resulting trench.
One type of form assembly used to define a trench includes a wooden form and strut structure. The wooden form includes a wooden frame which is covered with wooden sheets or planks to define a generally rectangular elongated trough. The wooden form is typically enclosed along its side and bottom faces, but may have an open top. Typically, a number of supporting wooden ribs are installed within the wooden form to increase the strength of the form so that it can withstand the relatively large pressures exerted by moldable trench forming compositions poured about it.
The wooden form is placed and secured within a preformed ditch. Cementitious material is typically poured up to the bottom face of the form and allowed to set in order to anchor the wooden form in the ditch. Then additional cementitious material is poured between the earthen walls of the ditch and the wooden sides of the form. Once all of the cementitious material has set, the wooden form is disassembled and removed from the trench.
Wooden forms are generally formed of lumber having a relatively rough exterior texture. Correspondingly, the inside surface of the trench formed by the wooden form is relatively uneven which reduces the efficiency of the flow of liquid through the trench. In addition, the assembly and disassembly of the wooden forms is both costly and labor intensive. The relatively large cost and labor required for assembly and disassembly of the wooden forms is increased in the formation of long trenches, and even further increased in the formation of trenches having a pitched or slanted bottom surface to facilitate drainage.
Commercially significant methods for forming trenches, together with improved removable forms for forming trenches, are disclosed in U.S. Pat. No. 5,281,051, which is assigned to the assignee of the present invention and incorporated herein by reference. In advantageous embodiments thereof, inexpensive forms are employed to form trenches instead of using the wooden forms discussed above. The trench forming assembly disclosed in U.S. Pat. No. 5,281,051 preferably includes opposing longitudinal frame members having a plurality of anchoring rods extending downwardly from the frame members. An elongated form body, preferably formed of relatively lightweight expanded polystyrene, includes aligned longitudinal slots in the opposed side walls for receiving the frame members. Horizontal portions of the frame members are secured within the longitudinal slots in the sidewalls of the form body during formation of the trench so that the frame members are held in alignment during the trench forming operation. In typical practice, one or more wires are wrapped around the outside of the form body and frame members to hold the frame members in the slots of the form.
Preferably the assembled form and frame members are placed into a prepared ditch by suspending the assembly from its top. Cementitious material is first poured around the bottom of the anchoring legs attached to the frame members and allowed to set in order to anchor the anchoring legs and, in turn, the frame members and the form within the ditch. Then more cementitious material is poured around the form body and allowed to set. Finally the form body is removed to expose the resulting trench and the properly aligned frame members. The removal of the form may be facilitated by a pair of slots extending upwardly into the form body from its bottom surface. By removing an upper portion of the form to access the slots as shown in U.S. Pat. No. 5,281,051, the form body can be more easily removed from the trench in several pieces.
Regardless of the fabrication technique, it is normally desirable to finish the trench with an elongated grate covering its open top in order to prevent people from unwittingly stepping in the open trench, to provide a smooth surface for vehicle travel, and/or to prevent relatively large objects from entering the trench and potentially blocking the flow of liquid therethrough. For a trench formed and described by U.S. Pat. No. 5,281,051, the grate is generally supported by a pair of spaced apart frame members which are set into and extend from the walls of the concrete trench. In order to stabilize the grate and to prevent the grate from rocking when weight, such as from a passing vehicle, is applied thereto, the frame members must be aligned in a common plane during the pouring and setting of the concrete about the form. If the frame members and, in turn, the grate are not properly aligned, the grate, the frame members and/or the cementitious trench itself may be damaged by the resulting movement of the grate. Accordingly, the alignment of the frame members in the moldable trench forming composition is important.
Grates are generally formed of a metal and are typically quite heavy. For example, trench grates frequently come in lengths of 0.5 meters and can weigh from 2 kg to over 150 kg. By way of further example, one common trench grate weighs about 25 kg. As such, grates are oftentimes merely set upon the frame members and are held in place by gravity, without utilizing any additional hardware to attach the grate to the frame members. Without any mechanical attachment of the grate to the frame members, the grate can advantageously be readily removed in order to access the trench, such as to clean the trench or remove some object from the trench. Unfortunately, the ease with which the grate can be removed also permits vandals or others to remove the grate, thereby creating an open trench that could be a hazard to individuals, vehicles, or the like. In addition, without any mechanical attachment of the grate to the frame members, the grate may become dislodged with passing vehicle traffic. Furthermore, in instances in which vehicular traffic passes lengthwise along the grate, forces imparted by the vehicles, particularly during braking or acceleration, may push the grate sections toward one end of the trench in the absence of any mechanical attachment of the grate sections to the frame, thereby potentially creating an undesired opening in the trench.
To secure the grate in the frame members, some conventional trench assemblies therefore include threaded bolts that extend vertically through corresponding openings defined by the grate and frame members. Such a design is disclosed in Great Britain Patent 2,234,001, wherein threaded bolts lock the grate to the underlying structure such that it cannot be jarred loose. However, trench assemblies using threaded bolts to secure the grate make the installation and removal of the grate difficult and time consuming. In addition, the rigid attachment of a grate to the underlying structure does not accommodate any differential in the thermal expansion and contraction of the grate and the underlying structure, such as the cementitious material that forms the trench itself. In this regard, metallic grates will expand to a substantially greater degree than the cementitious material that forms the trench as the temperature increases. This difference in expansion can damage the bolts, thereby making it quite difficult to thereafter remove the bolts in order to remove the grate. In fact, the difference in expansion may be so extreme as to actually shear off the bolts in a few instances. More commonly, however, the cyclic nature of thermal expansion and contraction may cause the bolts to loosen and back out, thereby loosening the attachment of the grate to the frame members. Thus, there is a need to provide a trench forming assembly wherein the gate is secured to the frame members, yet can be easily removed in instances in which it is desirable to remove the grate and access the interior of the trench while accommodating differences in the thermal expansion and contraction of the grate and the underlying structure, such as the cementitious material that forms the trench.
The present invention is directed to an improved trench forming assembly having an improved locking device for attaching and securing a grate over a trench or the like. According to the present invention, a removable pin is slidably positioned through an opening defined by an elongated frame member of the assembly and is engaged by a hook carried by the grate for securing the grate over the trench. Advantageously, while the angled position of the pin securely retains the grate, the pin can be easily removed in instances in which it is desirable to remove the grate and access the interior of the trench.
In particular, an assembly for forming a trench according to one embodiment of the present invention comprises a frame having two elongated members wherein each elongated member comprises an upstanding portion from which a support surface extends. The elongated members also define at least one opening therethrough, which in a preferred embodiment is positioned through a corner defined by the upstanding portion and the support surface. In one embodiment, each elongated member also includes a plurality of fixed pins extending inwardly therefrom and positioned in an alternating fashion with a plurality of openings. The frame also includes a plurality of leg members that are attached to and spaced along the elongated members. The leg members can have various shapes, such as an xe2x80x9cLxe2x80x9d shape or a xe2x80x9cUxe2x80x9d shape. In one embodiment, the leg members attach to both elongated members to help stabilize and further secure the elongated members.
The assembly also includes a removable grate that is disposed on the support surface of the elongated members. The grate has an upper surface and at least one hook that is disposed proximate at least one opening of the elongated members. In one advantageous embodiment, the grate defines at least one opening that is aligned with the at least one opening of the elongated members such that the portion of the grate proximate the opening and opposite the upper surface serves as the hook. In one embodiment, the grate comprises a first grate section and a second grate section, each having opposed ends and opposed lengthwise extending sides. Each grate section defines a groove proximate both one side and one end and extending at an acute angle relative to the upper surface. As before, that portion of each grate section proximate the groove and opposite the upper surface serves as a hook. Preferably, each grate section defines openings proximate each side and at each end, each of which extends at an acute angle relative to the upper surface. Advantageously, the grooves of adjacent grate sections are formed such that once the grate sections are placed end to end, the grooves of the adjacent grate sections are aligned, thereby collectively defining a complete opening.
The assembly can also include an end rail that bridges across the trench. The end rail includes an upstanding wall that defines a predetermined angle relative to the upper surface of the grate. In one embodiment in which the grate defines an opening proximate both one side and one end, the end rail also defines an opening proximate a side wall such that when the corresponding openings of the grate and the end rail are aligned they collectively define a complete opening. In this embodiment, the angle defined between the upper surface of the grate and the upstanding wall is about 90xc2x0. However, if the end of the grate proximate the end rail does not define an opening, such as if a grate section has been cut to size, the angle defined between the upper surface of the grate and the upstanding wall is preferably an acute angle and the respective end of the grate preferably defines a corresponding obtuse angle relative to the upper surface of the grate such that the respective end of the grate mates with the upstanding wall of the end rail to secure the grate.
The assembly also includes at least one removable pin that is slidably inserted through the respective openings defined by the grate, elongated members, and/or end rails and is mechanically engaged by the hook of the grate to releaseably secure the grate to the frame. The pin is preferably threadless, such as a threadless cylinder, although other designs that can slidably engage the openings can also be used.
Advantageously, the openings defined by the grate, elongated members, and end rails each preferably extend at a predetermined acute angle relative to the upper surface of the grate, such as about 45xc2x0, such that the removable pin can be easily removed from the openings if it is desirable to remove the grate. The predetermined angle is selected such that the removable pin at least partially held within the openings by gravitational forces so that the pin cannot readily be jostled or vibrated from the openings, while still being capable of being easily removed by hand, if desired. In addition, the grate is preferably sized to account for the differences in the thermal expansion and contraction of the grate and the cementitious material that forms the trench so that the pin continues to secure the grate to the frame as the grate and the cementitious material differentially expand and contract, and so that the pin does not become bound within a respective opening or broken by thermal expansion and can continue to be inserted and removed as the temperature changes.
According to one embodiment of the present invention, the assembly includes at least one sleeve member that is secured to a respective elongated member. Preferably, the sleeve member includes a tubular member defining a passageway that is aligned with a respective opening defined by the elongated member, such that a removable pin can be slidably inserted in the passageway to secure the grate. In particular, the tubular member includes an inwardly extending portion that extends through the respective opening defined by the elongated member, and an outwardly extending portion that extends away from the elongated member. The sleeve member also includes an outwardly extending fin that extends along the upstanding portion of the elongated member and defines a groove for receiving a cross tie or tie element that extends across the elongated members to bias the elongated members toward one another. In one embodiment, the sleeve member is connected to a leg member, so that leg member is connected to the elongated rail by way of the sleeve member.
Methods of forming a trench according to the present invention are also provided. In one embodiment, the method of forming a trench includes providing a form assembly comprising a frame as discussed above and a removable form engaged by the elongated members of the frame that defines the predetermined shape of the trench. The form assembly is positioned in the ditch, such as by securing the elongated members to a support frame or attachment using nails, tie wires, or the like, so that the form assembly is aligned in a fixed position. In one embodiment, the leg members of the form assembly are first secured by pouring a sufficient amount of a moldable trench forming composition, such as concrete or similar cementitious material, into the ditch. The moldable trench forming composition is then poured around the removable form and the composition sets around the form assembly to form the shape of the trench. After the trench has set, the form is removed.
A grate having at least one hook is then positioned on the support surface of the elongated members. Advantageously, the grate is releaseably secured to the elongated members by the pin that is slidably and removably inserted into a corresponding opening defined by the elongated member at a predetermined acute angle relative to the upper surface of the grate so as to also be mechanically engaged by the hook of the grate. In one embodiment, the pin also extends through a passageway defined by a sleeve member that is aligned with and is preferentially disposed within the opening defined by the elongated member. The pin is therefore positioned at a predetermined angle of less than 90xc2x0 relative to the upper surface of the grate, and preferably about 45xc2x0 relative to the upper surface of the grate.
In one embodiment, each elongated member defines a plurality of openings spaced therealong and includes a plurality of fixed pins extending inwardly therefrom that are positioned in an alternating fashion with the plurality of openings. To position a grate formed of multiple grate sections on the support surface of the elongated members, one end of each grate section is abutted against a respective fixed pin and thereafter the grate sections are placed upon the support surface. According to one embodiment of the present invention, each grate section defines at least one groove such that the portion of the grate section proximate the groove and opposite the upper surface of the grate forms the hook. In this embodiment, as the grate sections are laid down upon the support surface, the respective grooves defined therein are aligned to form a complete opening that is, in turn, aligned with a respective opening defined by the elongated member and, according to one embodiment, with the passageway defined by the sleeve member. By inserting a removable pin therethrough, the hooks of both adjacent grate sections engage the pin, thereby securing the grate sections to the frame.
Accordingly, the various embodiments of the present invention provide an important advancement in the state of the art by providing an improved system for securing a grate to the trench that is less difficult and time consuming compared to conventional systems. In particular, the slidably removable pin is capable of securing the grate when inserted in the corresponding opening defined by an elongated member and engaged by the hook carried by the grate, yet can be easily withdrawn from the openings such that the grate can be removed from the trench. In addition, the assembly advantageously accommodates differential expansions and contractions of the grate and the cementitious material that forms the trench. Moreover, the assembly restrains the grate from longitudinal movement otherwise caused by longitudinally directed forces, such as those forces created by the braking and acceleration of vehicles passing in a longitudinal direction along the grate.